Question

Silicon, which makes up about 25% of earth's crust by mass, is used widely in the modern electronics industry. it has three naturally occurring isotopes,28si,29si, and30si. calculate the atomic mass of silicon to 4 decimal places. isotope isotopic mass (amu) abundance (%) 28si 27.976927 92.23 29si 28.976495 4.67 30si 29.973770 3.10

Answer 1

Answer is: 28,0855 amu.
%abudance(²⁸Si) = 92,23% = 0,9223.
%abudance(²⁹Si) = 4,67% = 0,0467.
%abudance(³⁰Si) = 3,10 = 0,031.
isotopic mass(²⁸Si) = 27,967927 amu.
isotopic mass(²⁹Si) = 28,976495 amu.
isotopic mass(³⁰Si) = 29,973770 amu.
Ar(Si) = ( 27.976927 x 92.23) + ( 28.976495 x 4.67) + (29.973770 x3.10)/100
          = 28,0855 amu.